Multiple Choice Questions Topic Outline
- MCQs in Operating Point
- MCQs in Fixed-Bias Circuit
- MCQs in Emitter-Stabilized Bias Circuit
- MCQs in Voltage-Divider Bias
- MCQs in DC Bias with Voltage Feedback
- MCQs in Miscellaneous Bias Configurations
- MCQs in Design Operations
- MCQs in Transistor Switching Networks
- MCQs in Troubleshooting Techniques
- MCQs in PNP Transistors
- MCQs in Bias Stabilization
Begin and Good luck!
1. Which of the following currents is nearly equal to each other?
- A) IB and IC
- B) IE and IC
- C) IB and IE
- D) IB, IC, and IE
2. The ratio of which two currents is represented by β?
- A) IC and IE
- B) IC and IB
- C) IE and IB
- D) None of the above
3. At what region of operation is the base-emitter junction forward biased and the base-collector junction reverse biased?
- A) Saturation
- B) Linear or active
- C) Cutoff
- D) None of the above
4. Calculate the approximate value of the maximum power rating for the transistor represented by the output characteristics of Figure 4.1?
- A) 250 mW
- B) 170 mW
- C) 50 mW
- D) 0 mW
5. The cutoff region is defined by IB _____ 0 A.
- A) >
- B) <
- C) ≤
- D) ≥
6. The saturation region is defined by VCE _____ VCEsat.
- A) >
- B) <
- C) ≤
- D) ≥
7. For the BJT to operate in the active (linear) region, the base-emitter junction must be _____-biased and the base-collector junction must be _____-biased.
- A) forward, forward
- B) forward, reverse
- C) reverse, reverse
- D) reverse, forward
8. For the BJT to operate in the saturation region, the base-emitter junction must be _____-biased and the base-collector junction must be _____-biased.
- A) forward, forward
- B) forward, reverse
- C) reverse, reverse
- D) reverse, forward
9. Which of the following voltages must have a negative level (value) in any npn bias circuit?
- A) VBE
- B) VCE
- C) VBC
- D) None of the above
10. For what value of β does the transistor enter the saturation region?
- A) 20
- B) 50
- C) 75
- D) 116
11. Determine the reading on the meter when VCC = 20 V, RC = 5 kΩ, and IC = 2 mA.
- A) 10 V
- B) –10 V
- C) 0.7 V
- D) 20 V
12. Which of the following is assumed in the approximate analysis of a voltage divider circuit?
- A) IB is essentially zero amperes.
- B) R1 and R2 are considered to be series elements.
- C) βRE ≥ 10R2
- D) All of the above
13. It is desirable to design a bias circuit that is independent of the transistor beta.
- A) True
- B) False
14. Calculate the voltage across the 91 kΩ resistor.
- A) 18 V
- B) 9.22 V
- C) 3.23 V
- D) None of the above
15. Calculate the value of VCEQ.
- A) 8.78 V
- B) 0 V
- C) 7.86 V
- D) 18 V
16. Calculate ICsat.
- A) 35.29 mA
- B) 5.45 mA
- C) 1.86 mA
- D) 4.72 mA
17. Calculate VCE.
- A) 4.52 V
- B) –4.52 V
- C) 4.48 V
- D) –4.48 V
18. Calculate VCE.
- A) –4.52 V
- B) 4.52 V
- C) –9 V
- D) 9 V
19. Which of the following is (are) related to an emitter-follower configuration?
- A) The input and output signals are in phase.
- B) The voltage gain is slightly less than 1.
- C) Output is drawn from the emitter terminal.
- D) All of the above
20. Determine the values of VCB and IB for this circuit.
- A) 1.4 V, 59.7 µA
- B) –1.4 V, 59.7 µA
- C) –9.3 V, 3.58 µA
- D) 9.3 V, 3.58 µA
21. Calculate ETh for this network.
- A) −12.12 V
- B) 16.35 V
- C) −3.65 V
- D) 10 V
22. Calculate Rsat if VCE = 0.3 V.
- A) 49.2 Ω
- B) 49.2 kΩ
- C) 49.2 mΩ
- D) 49.2 MΩ
23. You can select the values for the emitter and collector resistors from the information that is provided for this circuit.
- A) True
- B) False
24. In the case of this circuit, you must assume that VE = 0.1·VCC in order to calculate RC and RE.
- A) True
- B) False
25. Which of the following is (are) the application(s) of a transistor?
- A) Amplification of signal
- B) Switching and control
- C) Computer logic circuitry
- D) All of the above
26. Calculate the storage time in a transistor switching network if toff is 56 ns, tf = 14 ns, and tr = 20 ns.
- A) 70 ns
- B) 42 ns
- C) 36 ns
- D) 34 ns
27. The total time required for the transistor to switch from the "off" to the "on" state is designated as ton and defined as the delay time plus the time element.
- A) True
- B) False
28. For an "on" transistor, the voltage VBE should be in the neighborhood of 0.7 V.
- A) True
- B) False
29. For the typical transistor amplifier in the active region, VCE is usually about _____ % to _____ % of VCC.
- A) 10, 60
- B) 25, 75
- C) 40, 90
30. Which of the following is (are) a stability factor?
- A) S(ICO)
- B) S(VBE)
- C) S(β)
- D) All of the above
31. In a fixed-bias circuit, which one of the stability factors overrides the other factors?
- A) S(ICO)
- B) S(VBE)
- C) S(β)
- D) Undefined
32. In a voltage-divider circuit, which one of the stability factors has the least effect on the device at very high temperature?
- A) S(ICO)
- B) S(VBE)
- C) S(β)
- D) Undefined
33. Use this table to determine the change in IC from 25ºC to 175ºC for RB / RE = 250 due to the S(ICO) stability factor. Assume an emitter-bias configuration.
- A) 140.34 nA
- B) 140.34 µA
- C) 42.53 nA
- D) 0.14034 nA
34. Determine the change in IC from 25ºC to 175ºC for the transistor defined in this table for fixed-bias with RB = 240 kΩ and β = 100 due to the S(VBE) stability factor.
- A) 145.8 µA
- B) 145.8 nA
- C) –145.8 µA
- D) –145.8 nA
35. Determine ICQ at a temperature of 175º C if ICQ = 2 mA at 25º C for RB / RE = 20 due to the S(β) stability factor.
- A) 2.417 mA
- B) 2.392 mA
- C) 2.25 mA
- D) 2.58 mA
Fill-in-the-blanks Questions
1. By definition, quiescent means _____.
- A) quiet
- B) still
- C) inactive
- D) All of the above
2. _____ should be considered in the analysis or design of any electronic amplifiers.
- A) dc
- B) ac
- C) dc and ac
- D) None of the above
3. For the dc analysis the network can be isolated from the indicated ac levels by replacing the capacitor with _____.
- A) an open circuit equivalent
- B) a short circuit equivalent
- C) a source voltage
- D) None of the above
4. In a fixed-bias circuit with a fixed supply voltage VCC’ the selection of a _____ resistor sets the level of _____ current for the operating point.
- A) collector, base
- B) base, base
- C) collector, collector
- D) None of the above
5. Changes in temperature will affect the level of _____.
- A) current gain β
- B) leakage current ICEO
- C) both current gain β and leakage current ICEO
- D) None of the above
6. In a fixed-bias circuit, the magnitude of IC is controlled by and therefore is a function of _____.
- A) RB
- B) RC
- C) β
- D) RB and β
7. For a transistor operating in the saturation region, the collector current IC is at its _____ and the collector-emitter voltage VCE is to the _____.
- A) minimum, left of the VCEsat line
- B) minimum, right of the VCEsat line
- C) maximum, left of the VCEsat line
- D) maximum, right of the VCEsat line
8. The dc load line is determined solely by the _____.
- A) base-emitter loop
- B) collector-emitter loop
- C) base-collector loop
- D) None of the above
9. A change in value of _____ will create a new load line parallel to its previous one in a fixed-bias circuit.
- A) RB
- B) RC
- C) VCC
- D) VBE
10. In a fixed-bias circuit, the slope of the dc load line is controlled by _____.
- A) RB
- B) RC
- C) VCC
- D) IB
11. The emitter resistor in an emitter-stabilized bias circuit appears to be _____ in the base circuit.
- A) larger
- B) smaller
- C) the same
- D) None of the above
12. _____is the primary difference between the exact and approximate techniques used in the analysis of a voltage divider circuit.
- A) Thevenin voltage ETh
- B) Thevenin resistance RTh
- C) Base voltage VB
- D) RC
13. The Thevenin equivalent network is used in the analysis of the _____ circuit.
- A) fixed bias
- B) emitter-stabilized bias
- C) voltage divider
- D) voltage feedback
14. The saturation current of a transistor used in a fixed-bias circuit is _____ its value used in an emitter-stabilized or voltage-divider bias circuit for the same values of RC’
- A) more than
- B) the same as
- C) less than
- D) None of the above
15. In a collector feedback bias circuit, the current through the collector resistor is _____ and the collector current is _____.
- A) IC’ IC
- B) IB + IC’ IC
- C) IB’, IC
- D) None of the above
16. _____is the least stabilized circuit.
- A) Fixed bias
- B) Emitter-stabilized bias
- C) Voltage divider
- D) Voltage feedback
17. _____ is less dependent on the transistor beta.
- A) Fixed bias
- B) Emitter bias
- C) Voltage divider
- D) Voltage feedback
18. In a transistor-switching network, the level of the resistance between the collector and emitter is _____ at the saturation and is _____at the cutoff.
- A) low, low
- B) low, high
- C) high, high
- D) high, low
19. In a transistor-switching network, the operating point switches from _____ to _____ regions along the load line.
- A) cutoff, active
- B) cutoff, saturation
- C) active, saturation
- D) None of the above
20. For the typical transistor amplifier in the active region, VCE is usually about _____ % to _____ % of VCC’
- A) 0, 100
- B) 25, 75
- C) 45, 55
- D) None of the above
21. In any amplifier employing a transistor, the collector current IC is sensitive to _____.
- A) β
- B) VBE
- C) ICO
- D) All of the above
22. As the temperature increases, β _____, VBE _____, and ICO _____ in value for every 10ºC.
- A) increases, decreases, doubles
- B) decreases, increases, remains the same
- C) decreases, increases, doubles
- D) increases, increases, triples
23. A significant increase in leakage current due to increase in temperature creates _____between IB curves.
- A) smaller spacing
- B) larger spacing
- C) the same space as at lower temperature
- D) None of the above
24. The _____the stability factor, the _____sensitive the network is to variations in that parameter.
- A) higher, more
- B) higher, less
- C) lower, more
- D) None of the above
25. In an emitter-bias configuration, the _____ the resistance RE’, the _____ the stability factor, and the _____ stable is the system.
- smaller, lower, less
- larger, more, more
- smaller, more, more
- larger, lower, more
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Note: Check your works. DC Biasing-BJTs - MCQs Answers
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